append to config file, not rewrite

install.py

@@ -206,8 +206,11 @@ def writeConfig(installdir, formdir):
     write one line per info, no line if info is None
     """
     try:
-        with open(CONFIGFILE, "w+") as configfile:
-            # w = write
+        with open(CONFIGFILE, "a+") as configfile:
+            # a = append
+            # if you use only the last entries in the configfile this is OK
+            # and you do not overwrite what might be interesting to
+            # the user
             # + = create if not exist
             if installdir is not None:
                 print(CONFIG_INSTALLDIR + CONFIG_SEPARATOR +